Description: (Applicant's Description) This facility covers maintenance of infrastructure and large shared equipment essential for research of all groups in E17/E18. This includes all darkrooms, X-ray processors and digital cameras; all fume hoods and all biohazard hoods; the CO2 supply for all incubators in E17/E18. It also covers various required safety operations and activities. Prof. J. Liu is the faculty supervisor for Shared Resources and the Investigator responsible for the CCR Safety Committee. He prepares safety reports such as the annual Chemical Hygiene Plan and the CCR Safety Plan. He works closely with W. DeHaro, the technical supervisor, to interface with the Safety Office, the Radiation Office and the Biosafety Office at MIT. Mr. DeHaro is responsible for routine repairs to equipment and coordination of more major repairs and for minor electrical and mechanical repairs, avoiding delays to work and research that would be inevitable if outside service companies had to be called. He also implements actions mandated by the CCR Safety Committee and MIT Safety Offices.